A conventional image forming device has a photosensitive drum and a developing device. The developing device has a casing on which a toner box for accommodating toner is mounted.
The toner box is formed in a shape having a circular circumferential surface, for example. The circular circumferential surface is formed with a toner discharge port for discharging toner toward an interior of the casing. The toner discharge port has a peripheral area provided with a seal member for preventing toner leakage. Further, a shutter is slidably movably provided at an outer periphery of the circular circumferential surface to open and close the toner discharge port.
After the toner box is mounted on the casing of the developing device, the shutter is slidingly moved to open the toner discharged port. As a result, a toner supply passage is defined between the toner box and the casing through the toner discharge port. Toner is supplied to the casing from the toner box via the toner supply passage.
In order to move the shutter to/from an open position in which the toner discharge port is open from/to a closed position in which the toner discharge port is closed, a gear provided at the shutter and a drive gear meshingly engageable with the gear are proposed. A drive force from the drive gear is transmitted to the gear for moving the shutter.